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Gloom about the performance of microbicide gels aimed at preventing HIV infection lifted a little yesterday (9 February) with the results of a major new trial.

The multi-site study gives a "strong indication", that the gel, PRO 2000, might protect against infection, say researchers. But the results were not completely certain.

The trial, which compared two gels for preventing the sexual transmission of HIV from men to women, follows the unsuccessful trial of Carraguard, the results of which were published last year (see Anti-HIV gel fails to prevent infection).

That trial led commentators to speculate that the way forward in HIV/AIDS-prevention lies in vaccines (see Drugs may be the next frontier for HIV prevention) or gels in combination with antiretroviral drugs.

In the latest trial, the Medical Research Council of South Africa (MRC) enrolled just over 3,000 women across seven sites in Malawi, South Africa, Zambia, Zimbabwe and the United States between February 2005 and September 2008.

The study compared BufferGel and PRO 2000 with a placebo gel and no gel.

Of the four groups, the lowest incidence of HIV was in the group using the PRO 2000 gel, showing a protective effect of 30 per cent. This falls short of the 33 per cent target considered statistically significant.

There was also evidence that, for those who used the gel frequently and condoms infrequently, there was an efficacy of 78 per cent.

None of the interventions was effective in preventing other sexually transmitted infections — or as a contraceptive.

"PRO 2000 is the first microbicide product, after ten years of research, that suggests that the use of a microbicide for HIV prevention will work," said Gita Ramjee, director of the MRC HIV Prevention Unit and principal investigator for the trials.

"For the first time there is hope that one day we will have a female-initiated option for HIV prevention. It is a huge step for microbicides and prevention ... and for the empowerment of women," she said.

"We do not have a proven microbicide," said University of KwaZulu-Natal professor Salim Karim, who presented the study findings at the 16th Conference on Retroviruses and Opportunistic Infections, in Montreal, Canada, yesterday.

"What we have is something that looks positive."

Researchers now await the results of a larger PRO 2000 study being conducted by the British Medical Research Council, whose results are due in December 2009.